Non-volatile memory systems, such as flash memory, have been widely adopted for use in consumer products. Flash memory may be found in different forms, for example in the form of a portable memory card that can be carried between host devices or as a solid state disk (SSD) embedded in a host device. As the non-volatile memory cell scales to smaller dimensions with higher capacity per unit area, the cell endurance due to program and erase cycling, and disturbances (e.g. due to either read or program) may become more prominent. The overall vulnerability of memory cells and the defect level during the silicon process may become elevated as the cell dimension shrinks and process complexity increases, which directly affects the data integrity at both the memory and system. In particular, temperature may cause disparities within a block or within a die regarding defects.
Data retention (DR) may be worse at higher temperatures because electrons for each of the charge values may be lost over time, which may eventually result in data loss. Increased temperatures may accelerate the electron loss. Likewise, extended time or exposure to high temperatures may result in a shift of the levels (i.e. thresholds). The use of a temperature sensor to monitor changing temperatures and adjust for the effects of higher temperatures may not be effective because the sensor only measures the local temperature at the location of the sensor and does not account for local changes in temperature. Accurately accounting for temperature effects on the blocks within a die may improve data retention.